Restructuring (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012 Workforce reduction plan	Dec. 31, 2011 Workforce reduction plan
Restructuring Cost and Reserve
Restructuring expenses			$ 2,200,000	$ 3,500,000
Employee severance, benefits and related costs	39,000	85,000	1,500,000
Write-down of raw material inventory due to facility closure			$ 700,000